title: NK cell natural cytotoxicity and IFN-gamma production are not always coordinately regulated: engagement of DX9 KIR+ NK cells by HLA-B7 variants and target cells.
abstract: DX9 mAb-binding killer cell-inhibitory receptors (KIR) recognize HLA-B molecules that express the Bw4 public serologic epitope. We assessed DX9+ NK cell fine specificity recognition of HLA-B7 variants and HLA-B27 alleles by 51Cr release natural cytotoxicity assays and by flow cytometry and enzyme-linked immunospot (ELISPOT) IFN-gamma synthesis and release assays. 721.221 target cell expression of Bw4+ HLA-B27 alleles specifically inhibited DX9+ NK cell natural cytotoxicity and IFN-gamma synthesis and release. A triple substitution of HLA-B7 at residues 80, 82, and 83 known to induce expression of the Bw4 serologic epitope also specifically inhibited DX9+ NK cell natural cytotoxicity and IFN-gamma responses. Single HLA-B7 amino acid substitution variants were recognized in the same decreasing rank order by DX9+ NK cells and Bw4-reactive mAbs: G83R > R82L > N80T = HLA-B7. Natural cytotoxicity inhibition was reversed by the presence of blocking DX9 mAb. Natural cytotoxicity and IFN-gamma production were coordinately regulated by a panel of HLA-B7 variants expressed on 721.221 cells, suggesting that these two effector functions are inhibited by the same KIR-mediated signaling mechanisms. In contrast, some NK cell clones killed 721.221 and K562 target cells equally well but released much more IFN-gamma in response to K562 target cells. Differential regulation of natural cytotoxicity and IFN-gamma release shows that NK cell effector functions respond to distinct signals.
authors.affiliation: Department of Pathology, University of Iowa, Iowa City 52242, USA.
authors.forename: Z B
authors.initials: ZB
authors.lastname: Kurago
authors.forename: C T
authors.initials: CT
authors.lastname: Lutz
authors.forename: K D
authors.initials: KD
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Colonna
mesh_terms: D000483:Alleles; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D002460:Cell Line; D002999:Clone Cells; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic; D000939:Epitopes / Q000502:physiology; D014644:Genetic Variation / Q000276:immunology; D015235:HLA-B Antigens / Q000276:immunology; D015793:HLA-B7 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D007694:Killer Cells, Natural / Q000145:classification / Q000276:immunology* / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D054340:Receptors, KIR
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D015235:HLA-B Antigens; D015793:HLA-B7 Antigen; C042388:HLA-Bw4 antigen; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D007371:Interferon-gamma